The capacitor is there to turn the RTS signal into a pulse, so that when the computer brings RTS low, it briefly pulls reset low, and then the pull-up resistor charges the capacitor again, bringing reset high again.

Source : http://www.gammon.com.au/forum/?id=11637

Can anyone tell me about this ? I do not understand why it needs so. And is DTR =RTS ? My FTDI programmer are using VCC, RXD, TXD, DTR,CTS and GND pins

The capacitor is there to turn the RTS signal into a pulse, so that when the computer brings RTS low, it briefly pulls reset low, and then the pull-up resistor charges the capacitor again, bringing reset high again.

Source : http://www.gammon.com.au/forum/?id=11637

Can anyone tell me about this ? I do not understand why it needs so. And is DTR =RTS ? My FTDI programmer are using VCC, RXD, TXD, DTR,CTS and GND pins

Thanks !

Why do you need to use DTR or RTS (yes you can use either but not both) ?

When you press upload on the Arduino IDE to upload a new sketch to an attached arduino board, the IDE needs to reset the attached arduino board so the bootloader on the board will start and communicate with the IDE to allow uploading the new sketch.

Simply a misprint on that site's pin out of the 6 pin FTDI pin out, where it says RST it should say RTS. Either the RTS or the DTR signal can be used to generate the auto reset pulse, as the arduino IDE uses both.